Method of and apparatus for porcelain enameling sheet metal



Sept. 30, 1947. R. s. CALTON 2,423,307

METHODS OF AND APPARATUS FOR PORCELAIN ENAMELINQ SHEET METAL Filed July 18, 1944 2- Sheets-Sheet 1 INVENTOR.

. ROBERT 6. (01.10.

Sept. 30, 1947. 'R.'G.'CALTON METHODS OF AND APPARATUS FOR PORCELAIN ENAMELING SHEET METAL 2 Sheets-Sheet 2 Filed July 18, 1944 EA C /v T p 5 EM Patented Sept. 30, 1947 METHOD OF AND APPARATUS FOR POR- CELAIN ENAMELING SHEET METAL Robert G. Calton, Nashville, Tenn.

Application July 18, 1944, Serial No. 545,467

12 Claims.

This invention relates to a method of applying and firing or fusing porcelain enamel on continuously moving, thin, sheet metal and, among other objects, aims to provide a novel method of enameling very thin sheets of pickled stock and maintaining the sheet undergoing treatment, taut throughout its length to prevent buckling or warping during the enameling process. Another aim is to provide improved apparatus whereby thin sheets may be enameled while fed longitudinally in a vertical plane and maintained under substantially uniform tension throughout the treatment. The idea is to produce thin, porcelain enameled sheets of stock sizes or lengths which can be cut to the desired size with shears and drilled in the field, so that they can be used in making panels in various types of buildings to take the place of ordinary tile or made-to-order pieces of enamel. A further idea is to provide such panels which do not hav to be custommade before they are applied and which can be fastened by ordinary screws or metal trim strips in much the same fashion as linoleum or the like. Furthermore, an important aim is to make it possible to apply porcelain enamel to very thin sheets which would collapse or sag and be ruined if the enamel were fused on in accordance with the usual methods.

Other aiins and advantages of the invention will appear in the specification when considered in connection with the accompanying drawings illustrating one embodiment of the invention for practicing the invention and, wherein:

Figure 1 is a diagrammatic, vertical sectional view showing one form of apparatus for practicing the method;

Figure 2 is a top plan view of a pair of adjustable gripping rollers;

Figure 3 is a side elevation of upper and lower gripping and tensioning rollers, parts being omitted and other parts being broken away and shown in section; and

Figure 4 is an end view taken at the left-hand end of the upper pair of rollers shown in Figure 2, parts being shown in section.

Heretofore, many unsuccessful attempts have been made to produce thin, porcelain enamel sheets capable of being cut with shears or tinners ships and applied with screws or other fastening elements so that they can b cut and applied in the form of wall panels for both exterior and interior use in various types of buildings. Because of the high temperature necessary to apply porcelain enamel on iron, it has been necessary to use heavy gauge metal to prevent warping, due to the heat necessary for firing. The thicknesses customarily used run from 16 to 20 gauge and are too heavy to be cut in the field. Therefore, it has been necessary to pre-fabricate the parts and, as a consequence, all such panels have been custom-made for a particular job. The present invention provides for the successful production of enameled sheets of a thickness from 26 to 32 gauge, which would ordinarily warp or partially collapse, due to the high temperatures to which the sheets are subjected during the firing operation. The invention also provides for overcoming the difiiculty, due to warpage 'of thin sheets, thereby making it possible to cut "the sheets with ordinary tinners ships, as well as 'to' bore holes with small boring tools, so that the sheets may be erected or applied with screws or metal trim strips such as are employed in the installation of linoleum walls. The production of such sheets also makes it possible for a dealer to carry stock-sized sheets in a great variety of colors and apply them on any job without having to order custom-made parts or panels.

Referring to the apparatus shown in the accompanying drawings, the method involves the continuous application of vitreous or porcelain enamel to a coil or roll of light gauge stock mounted on a horizontal spindle l I and the sheet passes downwardly through the apparatus between pairs of upper and lower tension rollers l2 and I3. The upper rollers l2 are shown as being supported by base plates [4 and both rollers are mounted on pivoted bearing arms l5 carried by upstanding brackets [6 on the base plates. The gripping pressure of the rollers can be adjusted by spring-urged plungers I! and the tension of the springs is controlled by adjusting nuts l8. The base plates I4 are shown as being'mounted on compression springs l9 resting on frame members or boards 20 and are guided by vertical pins 2|. The compression of the springs 19 is adjusted by nuts 22 mounted on stud bolts 23 passing through the convolutions of the springs and into the upper frame members 20. The stud bolts 23 also pass through flanges 24 of the brackets It on which the bearing arms l5 are pivoted.

As shown in Figure 1, a coil or roll of sheet metal of the proper thickness is gripped between the upper rollers and passes downwardly through a spray chamber 25, indicated as having a series of spray heads 26 for applying vitreous enamel paste on both sides of the sheet. The sheet then passes through an opening or slot in the lower wall of the chamber into a firing chamber 21, shown diagrammatically as being heated electrically by resistance elements 28. Of course. it will be understood that the heat may be applied in any suitable manner. Also, the chamber is shown as being suitably lined with heat retaining material.

The fired sheet passes through a slot in the bottom of the chamber 21 into a cooling chamber 29, illustrated as .being cooled by a heat-exchanging coil 30 which may be supplied with water or other cooling medium.

3 The sheet passes through a slot in the bottom of the cooling chamber and between the lower pair of rollers 13, which are mounted in the same fashion as are the upper rollers, being suspended below the bottom of the cooling chamber and guiding the sheet through a slotted base 3!, as When the sheet is initially threaded between the rollers, the rollers are shown in Fig. 1.

opened up by manipulation of the adjusting nuts l8 and then they are gripped against the sheet. The tension of the sheet between the rollers is adjusted by manipulation of the adjusting nuts 22. The idea is to keep the sheet under sufficient ously feeding a sheet longitudinally; applying frit paste and firing the moving sheet; and maintaining the sheet under suihcient tension to prevent warping due to the firing temperature.

4. Apparatus for applying porcelain enamel to thin sheet metal comprising, in combination, a

" horizontal spindle for carrying a roll of pre-picktension to eliminate warpage while it is held ve rtically stretched between the rollers. It will be understood that other types of gripping and tensioning means may be employed. In order to prevent the escape of'he'at upwardly from the firing chamber, through the spray chamber, and the top of the housing,'there is shown a, heat-retaining hood 32 composed of sheet metal or heat insulating material and adapted to be moved up and down with the upper roller assembly when it is adjusted vertically. In this instance, the hood is box-shaped and its lower edges are slidably mounted between the flanges of angle members 33 to make a slip joint. A similar hood 34 rests on the lower rollers l3 and guided to slide up and down with th rollers by angle flanges 35 to eliminate updraft of air around the rollers.

The rollers may be power driven by any suitable means. In this instance, each pair is geared together by a pair of spur gears 36,-and one of each pair of roller shafts carries a bevel gear 31. The two gears 31 are shown as meshing with spring-urged bevel gears 38 on a shaft 39, to allow for vertical adjustment of th rollers. The lower shaft is shown as having a driving pulley 40 oonnectedto be driven by a motor 4| by means of a belt 42. I

From the foregoing description, it will be seen that the method eliminates buckling of thin sheets due to the firing heat and the apparatus is relatively simple in its construction. The sheets are fed continuously through the apparatus at the proper speed and may be cut off when they pass out of the machine, and'piled up in stock lengths. In some cases, the sheets may be doubled back through the apparatus by passing over relatively large rollers to avoid sharp bends i. The method of enamelingthin sheet metal which is characterized by continuously feeding a sheet downwardly; maintaining the sheet under tension to prevent buckling; applying frit paste to the sheet; then subjecting the sheet to firing heat; and cooling the fired sheet before the tension is released.

2. The method of applying porcelain enamel to thin sheet metal capable of being cut with ordinary shears which is characterized by continuously feeding a sheet longitudinally and downwardly through a succession of treating chambers and under sufiicient tension to prevent buckling;

continuously applying frit paste to both sides of led sheet stock; upper and lower pairs of gripping and tensioning rollers; means for adjusting the tension on the sheet between the pairs of rollers; and successive spraying, firing and cooling chambers between the pairs of rollers.

5. Apparatus for applying porcelain enamel to thin sheet metal comprising, in combination, a horizontal spindle for carrying a roll of pre-pickled sheet stock; upper and lower pairs of gripping and tensioning rollers; means for adjusting the tension on the sheet between the pairs of rollers;

. successive sprayin firin and cooling chambers between the pairs of rollers; and power means connected to drive both pairs of rollers.

6. Apparatus, as set forth in claim 4, wherein the tension means includes springs and adjusting nuts associated with the rollers.

7. Apparatus, as set forth in claim 5, wherein the gripping and tension rollers are adjustable vertically and laterally and subjected to spring pressure.

8. Apparatus, as set forth in claim 5, wherein a vertically adjustable heat retaining hood is mounted around the upper pair of rollers.

9. The method of applying porcelain enamel to thin sheet metal, which is characterized by continuously feeding a sheet through a succession of treating chambers; maintaining the sheet under adjusted tension in the chambers to prevent buckling; continuously applying frit paste to the movin sheet in the first chamber; and firing and cooling the sheet in the other chambers.

-10.'The method of applying porcelain enamel tolthin sheet metal, which is characterized by continuously feeding a sheet through successive treating chambers; maintaining the sheet under adjusted tension to prevent buckling; continuously applying frit paste to the moving sheet in one chamber; firing the sheet in another chamher} and cooling the fired sheet.

11. The method of porcelain enameling sheet metal which is so thin that it would collapse if supported on rests during the fusion of the enamel thereon, which comprises suspending a length of such sheet metal between spaced supports; coating-and firing the sheet in the suspended area thereof; and maintaining the suspended sheet under sufiicient tension to prevent permanent warping due to the firing temperature.

'lZL The method of porcelain enameling sheet metal which is so thin that it would collapse if supported on rests during the fusion of the enamel thereon, which comprises progressively feeding such sheet longitudinally past spaced supports by which such sheet is suspended therebetween; coating and firing the sheet in the suspended area thereof; and maintaining the suspended portion of the sheetunder sufiicient tension to prevent permanent warping due to the firing temperature.

ROBERT G. CALTON. 

